Question

Four students reported their study time and test score from a statistics course and their data have been converted into Z scores in the table below. What is Pearson's correlation coefficient from this data set?

Group of answer choices

a.)-.50

b.)-.25

c.).75

d.)-1.00

In what situation would a researcher use
a *t-*test used instead of a *Z-*test?

Group of answer choices

a.)When there is only one sample.

b.)When the population standard deviation is unknown.

c.)When the sample size is smaller than 30.

d.)When the population is normally distributed.

If you conduct a two-tailed test at the .05 level of
significance, with a degree of freedom of 30, what would be your
critical *t* score on the *t* distribution?

a.)±2.043

b.)±1.729

c.)2.043

d.)1.729

A researcher tested a research hypothesis that people with
diagnosed depression will have REDUCED level of depressive symptoms
after a cognitive therapy treatment, as compared to the
pre-treatment level of depressive symptoms. The cutoff *t*
value is -1.746 for this one-tailed test. The data analysis yielded
a mean change score (post-treatment minus pre-treatment) of -3. If
the standard error is 2.0, what is the *t* statistic and
what is the conclusion of the hypothesis test?

Group of answer choices

a.)-1.50; fail to reject the null hypothesis

b.)-1.50; reject the null hypothesis

c.)-1.25; fail to reject the null hypothesis

d.)-1.25; reject the null hypothesis

Answer #1

1)Since study time and test scores are directly related to each other ( as study time increases test scores also increase) the correlation coefficient will be positive value.

r = 0.75

Negative scores indicate inverse relationship.

2) t test and z assume that population should be normally distributed and both can be used to test single population mean .

Z test assumes that population standard deviation is known.

Correct option : when population standard deviation is unknown.

3) critical value of t for two sided test at df 30 is equal to +- 2.043. When test is two sided it's critical region is equally divided on two sides of distribution. Therefore there are two critical values . Positive critical values are only for right tailed test.

4) t = mean change score/ standard Error

t = -3/2 = - 1.5

| - 1.746 | > | -1.5 | , we fail to Reject Null hypothesis.

A two-tailed hypothesis test is being used to evaluate a
treatment effect with α = .05. If the sample data produce a z-score
statistic of z = -1.24, then what is the correct decision?
Reject the null hypothesis and conclude that the treatment has
no effect.
Reject the null hypothesis and conclude that the treatment has
an effect.
Fail to reject the null hypothesis and conclude that the
treatment has an effect.
Fail to reject the null hypothesis and conclude...

Question #3
A researcher is conducting and experiment to evaluate a
treatment that is expected to increase the scores for individuals
in a population. If the researcher uses a one-tailed test with ( a
= .01), then which of the following correctly identifies the
critical region?
A. z > 2.33
B. z > 2.58
C. z < 2.33
D. z < 2.58
Question #4
A researcher evaluates a treatment effect using a two tailed
hypothesis test with ( a =...

An independent-measures research study uses two samples, each
with n = 8 participants. If the data produce a t statistic of t =
2.50, then which of the following is the correct decision for a
two-tailed hypothesis test? Group of answer choices Reject the null
hypothesis with a = .05 but fail to reject with a = .01. cannot
answer without additional information Reject the null hypothesis
with either a = .05 or a = .01. Fail to reject the...

The average test score for the statistics course is 74%. A
professor wants to see if the average test score for students who
are given colored pens on the first day of class is higher. The
test scores for the 12 randomly selected students who were given
the colored pens are shown below. Assume that the distribution of
the population is normal.
81, 61, 86, 63, 74, 91, 62, 70, 80, 94, 70, 87
What can be concluded at the...

For your answers pick one
*A researcher was interested in inspecting the effect of
classical music on stress among New York students. She studied a
sample of 30 New York students. She found that z= -3.00. Using a =
0.5(two-tailed), what can she conclude?
-Reject the null hypothesis and conclude that classical music
has no effect on stress levels
-Reject the null hypothesis and conclude that classical music has
no effect on stress levels
-Failed to reject the null hypothesis...

Some researchers claim that herbal supplements improve human
memory. To test this claim, a researcher selects a sample of n = 25
college students. Each student is given herbal supplements daily
for 6 weeks and then all the participants are given a standardized
memory test. For the population, scores on the tests are normally
distributed with µ = 70 and σ= 15. The sample of n = 25 students
had a mean score of M = 75. Can we conclude...

1a
The following data were obtained from an independent-measures
research study comparing three treatment conditions.
I
II
III
2
5
7
5
2
3
0
1
6
1
2
4
2
2
T =12
T =10
T =20
G = 42
SS =14
SS =9
SS =10
ΣX2= 182
Use an ANOVA with α = .05 to determine whether there are any
significant mean differences among the treatments.
The null hypothesis in words is
Group of answer choices
a. There...

5) A t test comparing a person's score on a test before and
after an intervention yields a p value of .08 (p = .08). What
should you do about the null (H0) hypothesis? Group of answer
choices
a. Reject H0
b. Do not reject H0
c. Accept H0
6)If the null (H0) hypothesis is true, then no difference exists
between populations. Group of answer choices
True
False
7) In an ANOVA, if there is no difference between the groups,...

An SAT prep course claims to improve the test score of students.
The table below shows the scores for seven students the first two
times they took the verbal SAT. Before taking the SAT for the
second time, each student took a course to try to improve his or
her verbal SAT scores. Do these results support the claim that the
SAT prep course improves the students' verbal SAT scores?
Let d=(verbal SAT scores prior to taking the prep
course)−(verbal...

An SAT prep course claims to improve the test score of students.
The table below shows the scores for seven students the first two
times they took the verbal SAT. Before taking the SAT for the
second time, each student took a course to try to improve his or
her verbal SAT scores. Do these results support the claim that the
SAT prep course improves the students' verbal SAT scores? Let
d=(verbal SAT scores prior to taking the prep course)−(verbal...

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